I've been asked to map an upgrade plan for the various handhelds that are currently deployed. This is easy enough to say that all 5810/6710/6280 etc will be upgraded to our latest supported device. However, I'm trying to find out when these older devices were made available so that I can quantify that model "abc" is x years old.

Does anybody know of a document (or source) referencing the history of model releases?

I guess the 850s, 950s, 857s and 957s are too old to be mentioned.
There's also the 5820, 6210, 6230, 7210 and 7230 to consider.

My initial question and research on this was quite selfish; I was only interested in the models that we currently have active. I am glad to see others are participating and adding their entries to give us all a better overall look at the release cycle for the Blackberry's.